Remove simplejson because it's no longer used by webkitpy

Remove simplejson because it's no longer used by webkitpy
https://bugs.webkit.org/show_bug.cgi?id=78164

Reviewed by Eric Seidel.

All the importers of this code were removed in a previous patch.

* Scripts/webkitpy/thirdparty/simplejson: Removed.
* Scripts/webkitpy/thirdparty/simplejson/LICENSE.txt: Removed.
* Scripts/webkitpy/thirdparty/simplejson/README.txt: Removed.
* Scripts/webkitpy/thirdparty/simplejson/__init__.py: Removed.
* Scripts/webkitpy/thirdparty/simplejson/_speedups.c: Removed.
* Scripts/webkitpy/thirdparty/simplejson/decoder.py: Removed.
* Scripts/webkitpy/thirdparty/simplejson/encoder.py: Removed.
* Scripts/webkitpy/thirdparty/simplejson/jsonfilter.py: Removed.
* Scripts/webkitpy/thirdparty/simplejson/ordered_dict.py: Removed.
* Scripts/webkitpy/thirdparty/simplejson/scanner.py: Removed.
* Scripts/webkitpy/thirdparty/simplejson/tool.py: Removed.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@107141 268f45cc-cd09-0410-ab3c-d52691b4dbfc